You want to first feed them a big meal, then let them settle down for a nap. Go over to them with the clippers and first just pick up their back paw and hold it lightly in the palm of your hand, if they jerk away, wait a few minutes and hold it again, actually don't hold it, lay it in the palm of your hand. Do this a couple of times. Then just lightly touch their toes, one at a time, if the cat jerks away, then just walk away. Do this every day for just a few minutes at a time until the cat is resigned to the fact that this is happening and does not jerk away. Once that happens, take the clippers and hold them like you are GOING to cut, but don't. Make sure the cat is not going to jerk away, then proceed to lightly cut off just the tip of the nail. Be careful not to cut into the quick, but I always have a septic pencil nearby just in case.
One way to not even worry about clipping claws is to buy your kitty a wooden scratching post. Her sharpening her claws on such hard wood will actually blunt them.